Valve-gear for steam-engines



H. R. BARNHURST. Valve Gear for Steam Engine.

No. 232,800. Patented Oct. 5,1880.

WI IJ E5555.

UNITED STATES PATENT OFFICE.

HENRY R. BARNHURST, OF ERIE, PENNSYLVANIA.

VALVE-GEAR FOR STEAM-ENGINES.

SPECIFICATION forming part of. Letters Patent No. 232,800, dated October5. 1880,

Application filed February 20, 1880.

To all whom it may concern Beit known that I, HENRY R. BARNHURST, acitizen of the United States, residing at Erie, in the county of Erieand State of Pennsylvania, have invented certain new and use fulImprovements in Valve-Gears for Steam- Engines; and I do hereby declarethe following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to whichitappertains to make and use the same, reference being had to theaccompanying drawings, and to letters or figures of reference markedthereon, which form a part of this specification.

The object of my invention is to provide in the valve-gear of asteam-engine a variable cut-off.

My invention consists in the arrangement of mechanism in the valve-gearof an oscillating or slide valve of a steamengine which shall operate insuch a manner that the valve is permitted to open by one eccentric at afixed point in relation to the stroke, and is closed by the action ofanother eccentric, which is movable upon the shaft, and may be variablyadjusted or controlled by a governor upon the shaft or elsewhere in sucha manner as to determine the point of closing said valve, which will beaccording to the difference of the angular advance of the twoeccentrics.

By my device the one valve is alternately under the control of the twoeccentrics. I use a spring or some equivalent device to open the valve,one of the eccentrics acting to permit it to open, but the valve isclosed by the other eccentric.

My device is capable of much diversity as to form, but its operationwill always be substantially as generally defined above.

In the accompanying drawings I have illustrated the device as connectedwith one of the oscillating valves of a Gorliss engine, the valve andseat being only snfficiently shown to clearly show the working of avalve when my invention is attached thereto.

In the drawings, Figure l is an elevation of my valve-gear, and showsthe position of parts when the valve is about to open the port. Fig. 2is a like view, but shows the position as when the valve has justclosed. Fig. 3 is a reverse view with parts in same position as in Fig.2.

The line 00 represents the position of the crank and the arrow thedirection of revolution of the crank. The arrow on the valve shows itsdirection of movement.

A and B are the two eccentrics on thecrankshaft. a and b are theeccentric-rods. G is the valve-stem; V, the valve; S, the valve 0 is acrank-plate extend.

seat; P, theport. ing from the valve-stem O. A and B are false cranks,and are loosely pivoted on the valvestem 0, and are connected with theeccentricrods to and b respectively. D D are springs, which operate uponthe crank O to open the valve when permitted to do so, by the eccentricB drawing back the false crank B.

In Fig. l the eccentric B is shown as about to draw back the false crank13 and permit the springs D to open the valve, and when this occurs thevalve will move in the direction of the arrow in that figure until theeccentric A advances the false crank A and checks its movement and turnsit back. In Fig. 2 this is shown to have taken place, and the device hasadvanced so as to close the valve over the port. The eccentric A willcontinue to advance the valve in the direction of the arrow shown inFig. 2 throughout the remainder of the movement in that direction, whenthe false crank B will have advanced so as to come in contact with thecrank-plate G. The false crank B will then, in proper time recede so asto permit the valve to return and open the port, during which time thefalse crank A has moved back, and is again advancing to act upon thecrank-plate O and move the valve to the cut-off. Thus it will be seenthat the two eccentrics alternately control the valve. The time at whichthe false crank A advances to move the valve to close the induction-portdepends upon the position of said eccentric upon the shaft, and this canbe adjusted to suit, or it may be automatically regulated by a governingdevice, and thus is the cut-off variable.

In place of placing the crank-plate O and the false cranks A B on thestem of the valve, they may be placed on the shaft of afaceplate andconnecting-rods be used to connect with the valves.

In place of the springs D shown any form of spring may be used, or theequivalent of a spring. And if it is found in any form of valve that thepressure of steam upon the valve tends to overcome the action of thespring, an equivalent of a spring in the form of a livesteam pistonchamber may be used, which would obviate that difficulty.

By suitable modifications, which will readily suggest themselves to askilled mechanic, my device may be applied to any form of valve.

In such engines as are constructed so as to open the valve by thepressure of steam upon the same, as apuppet or piston valve, no sprin gor equivalent thereof will be required.

What I claim as new is 1. 1n the valve-gear of a steam-engine, thecombination of a fixed and a variable eccentric upon the crank-shaft,and means, substantially as shown, whereby the steam-valve of the engineis alternately under the control of said eccentrics during eachrevolution of the crankshaft, .for the purposes mentioned.

2. The mechanical movement herein shown, consisting of a shaft with afixed and a variable eccentric thereon, a second shaft having acrank-plate rigidly attached thereto, and two false cranks looselycollared thereon, which latter are connected with said eccentricsrespectively, and alternately act upon said crankplate during therevolution of the former shaft, and thereby oscillate the latter shaftwithin an are which may be varied in length as the variable eccentric isadjusted, substantially as set forth.

3. In a steam-engine which has avalve provided with means whereby itwill open automatically when permitted so to do, the combinationtherewith of a variable and a fixed eecentric upon the crank-shaft,which alternately control the action of said valve, substantially as setforth.

In testimony whereof 1 affix my signature in presence of two witnesses.

HENRY R. BARN HURST.

Witnesses:

J NO. K. HALLOGK, FRANK H. BALL.

